JPS60245904A - Method and device for warming up steam turbine for driving boiler feed pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a warm-up method and apparatus for a steam turbine for driving a boiler feed water pump (hereinafter abbreviated as a BFP turbine), and more specifically, to a warm-up method and apparatus for a steam turbine for driving a boiler feed water pump (hereinafter referred to as a BFP turbine), and more specifically to a warm-up method and apparatus for a steam turbine for driving a boiler feedwater pump (hereinafter referred to as a BFP turbine). The present invention relates to a method and apparatus for warming up a high-pressure steam introduction section that introduces main steam as a heat source.

[Background of the invention]

Generally, in large-capacity power generation steam turbines, the boiler feed water pump is operated in R to increase the thermal efficiency of the power generation plant.
A method of driving by an FP turbine is adopted.

In addition, RFP turbines generally have one main turbine with
There are two units with 50% capacity.

There are two types of power steam sources for the RF P'methane: high pressure steam and low pressure steam. By high pressure steam we mean the main steam from the boiler, and by low pressure steam we mean relatively low temperature, low pressure steam extracted from the exhaust of a suitable stage of the pipe, for example an intermediate pressure turbine.

When the main turbine is operating under high load, the low pressure steam extracted from the main turbine has sufficient thermal energy to cover the output required by the RFP turbine, so the main steam is introduced as high pressure steam. is not necessary. but,
When starting the main turbine or when the main turbine is operating at low load, sufficient driving force cannot be obtained because the thermal energy of the low-pressure steam flowing to the BFP turbine is low (zero when the main turbine starts). . To avoid this, it is necessary to introduce high pressure steam to the RFP turbine. - As mentioned above, high-pressure steam is the main steam, and its steam conditions are generally 169 to 246 kglon"g% and 530 to 566 C. Since such high-temperature and high-pressure steam is used, the BFP turbine Warming up the high-pressure steam introduction section is essential to protect the RFP turbine from excessive thermal stress.As mentioned above, low-pressure steam has a low temperature, so there is no need to warm it up.

Recently, due to the electric power situation, power generation plants have tended to operate at high loads during the day and at low loads at night, or to operate continuously at medium or low loads, which is the so-called middle operation. Of the two BF'P turbines, one is operated when the main turbine load is 50% or more, and two BF'P turbines are operated when the main turbine load is 50% or more. Therefore, when the main turbine shifts from low load to high load operation, it is necessary to operate one stopped RFP turbine. In this case, before starting the stopped BFP turbine, it is necessary to warm up the high pressure steam introduction section of the BFP turbine.

FIG. 1 shows a high-pressure steam system and a low-pressure steam system for one RFP turbine, and FIG. 2 shows a high-pressure steam introduction section and a conventional warm-up technique.

As shown in FIG. 1, a high pressure steam system A and a low pressure steam system B are connected to the BFP turbine 1.

The high-pressure steam system A includes high-pressure steam pipes 2a to 2C, an electric high-pressure steam valve 3, and a high-pressure main steam stop valve (hereinafter referred to as H).
(abbreviated as P-MSV) 4 and high pressure steam control valve (hereinafter referred to as HP
- CV) 5 and these HP -Msv4 and u
-y-s-stro of p-CVs, first drain system connected to chest 6 of HP/MSV4, and HP-C
A second drain system connected to the chest 6 of V5, a warm-up system connected to the chest 6 of the same HP-CV5, and a leak steam system in the gap between the valve stem 4' and the chest 6 of HP-MSV4. 15, a leak steam system 16 in the gap between the valve stem 5' of the HP-CV5 and the chest 6, and a temperature measuring device 17. The high-pressure steam artificial valve 3 is provided to isolate the RFP turbine 1 from the high-pressure steam system Rh. The HP-M8V4, HP-CV5, and the chest 6 containing them constitute a high-pressure steam introduction section. The HP/MSV4 is hydraulically driven to open and close, and the BFP is activated in an emergency.
It is provided to block steam flowing into the turbine 1. The HP-CV 5 is configured to be opened and closed by a hydraulically driven control device (not shown), and is operated to open and close the RFP turbine 1 in response to a request signal from a boiler (not shown).
It is provided to control the amount of steam flowing into the The first drain system includes drain pipes 7a to 7C, a manual drain discharge valve 8, and an electric drain discharge valve 9, and includes high pressure steam pipes 2a to 2C and the HP-MSV4O chest 6.
In addition to discharging the internal drain to a blow tank (not shown), it is also used to warm up the high-pressure steam introduction section. The second drain system includes drain piping 108 to IOC, a manual drain discharge valve 11, and an electric drain discharge valve 12, and connects the drain inside the chest 6 of the HP/CV 5 to the condenser of the main turbine. It is also used to warm up the high-pressure steam introduction section.

The warm-up system includes a warm-up steam pipe 13a.

13b and an orifice 14, the BFP turbine 1
The orifice 14 is provided to constantly warm up the high-pressure steam introduction part during standby in preparation for restarting the main turbine. It is designed to be put into the condenser.

On the other hand, the low-pressure steam system B is configured almost the same as the high-pressure steam system A, and includes low-pressure steam pipes 182 to 18c, an electric low-pressure steam valve 19, and a low-pressure main steam stop valve 20.
A low pressure steam control valve 21 is provided. Although this low-pressure steam system B requires a drain system (not shown),
Because low-temperature, low-pressure steam flows, a warm-up system is not required.

By the way, in the high-pressure steam system A, in order to make the equipment more compact, the HP-MSV 4 and the HP-CV 5 are housed in a common chest 6, as shown in FIG.

Since high-temperature, high-pressure main steam enters the chest 6, the chest 6 has a very thick wall, and also has a complicated structure because it contains the HP/MSV4 and HP-CV5. be. Therefore, when high-temperature, high-pressure main steam is introduced, there is a large temperature difference between the inner and outer walls of the chest 6, and excessive thermal stress is generated in the chest 6. If thermal stress is repeatedly applied to the chest 6, cracks will occur, leading to a serious accident. Therefore, warming up the chest 6 is absolutely necessary.

Next, a conventional method for warming up the high-pressure steam introduction section will be explained.

One method is as follows using a system attached to the high pressure steam system A shown in Figures 51c1 and 2.

When starting up the RFP turbine 1, the high pressure steam valve 3, HP/MSV4 and HP/CV5 are fully closed, and the drain/discharge valves 8, 9 and 11.12 are fully open before warming up. There is.

Therefore, first open the high pressure steam valve 3. As a result, the high-temperature, high-pressure main steam is transferred from the high-pressure steam pipe 2a to the high-pressure steam valve 3.
→It passes through the high pressure steam pipe 2b and is introduced into the chest 6 of HP/MSV4. Here, since the HP-MSV 4 is fully closed, steam is passed from the inside of the chest 6 through the drain pipe 7a of the first drain system →, the drain discharge valve 8 → the drain pipe 7b → the drain discharge valve 9 → the drain pipe 7C. , is discharged into the blow tank. Further, the leak steam from the gap between the valve stem 4' of the HP-MSV 4 and the chest 6 passes through the leak steam system 15 and is recovered as heat to the grand steam system (not shown). During this time, the inner surface of the chest 6 of the HP-MSV4 is warmed up.

After warming up the inner surface of the chest 6 of the HP-MSV4, the HP-MSV4 is then opened. Accordingly, the main steam is HP-
The steam is introduced from the MSV4 into the chest 6 of the HP-Cv5, and a part of the steam is transferred to the drain pipe 1 of the second drain system.
0a→drain discharge valve 11→drain pipe 10b→drain discharge valve 12→drain pipe 10C to be discharged to the condenser of the main turbine, and the other part of the steam is discharged to the warm-up steam pipe 131 of the warm-up system→orifice 14→This is also discharged to the condenser of the main turbine via the warm-up steam pipe 13b. Also,
Leak steam from the gap between the valve stem 5' of the HP-CV5 and the chest 6 passes through the leak steam and air system 16 and is heat-recovered to the ground steam system. This warm-up is continued until the chest 6 reaches the warm-up completion target temperature. This warm-up completion target temperature is approximately 50% of the rated temperature of the main steam.

The completion of warm-up is determined by the temperature measuring device 17.

After warming up, the first step is The electric drain discharge valves 9 and 12 of the second drain system are fully closed so that the main steam can be vented to the RFP turbine 1 at any time. Warming up of the high-pressure steam introduction section in this state is performed by constantly discharging main steam from the warm-up system via the inside of the chest 6. Therefore, the high-pressure steam introducing section can be maintained in a warmed-up state at all times.

FIG. 6 shows the temperature of the high-pressure steam introduction section according to the warm-up method.

However, in the above-mentioned conventional technology, main steam is constantly flowing into the warm-up system from the high-pressure steam introduction section as warm-up steam.
Thermal energy is wasted, resulting in a decrease in thermal efficiency and, in turn, a decrease in performance.

Next, another conventional warming-up method that is an improvement on the above-mentioned warming-up method will be described.

In this warm-up method, the warm-up system including the warm-up steam pipes 13a, 13b and the orifice 14 is removed from the systems attached to the BFP turbine l shown in FIG.
The V4 and the electric drain discharge valve 12 of the second drain system are opened and closed alternately to warm up the high ball introduction section.

That is, before opening the high pressure steam valve 3, the HP-MSV
4 Oh! and HP-CV5 are fully closed, the electric drain discharge valves 9 and 12 of the first and second drain systems are fully opened, and the manual drain discharge valves 8 and 11 are opened. Note that the manual drain discharge valves 8 and 11 are replaced with electric drain discharge valves 9 and 1.
It closes when 2 fails, and is normally fully open.

The HP-MSV4 and HP-CV5 are fully closed, the drain discharge valves 9 and 12 are fully opened, and the drain discharge valves 8 and 11 are fully closed.
From the open state, open the high pressure steam artificial valve 3, and drain the drain etc. in the high pressure steam pipes 28 to 2C to the drain pipe 7a of the first drain system → drain discharge valve 8 → drain pipe 7b → drain discharge valve 9 → drain The drain discharge valve 12 of the second drain system is one for discharging to the blow tank through the pipe 7C.
After closing the HP-MSV4, open the main steam to HP-C
V5 is introduced into the chest 6 and warmed up, and after the set time elapses, the I(P-MSV4 is closed. Then, the drain discharge valve 12 of the second drain system is fully opened, and the stagnant drain in the chest 6 or The steam is discharged to the condenser of the main turbine via the drain pipe 10a of the second drain system→drain discharge valve 11→drain pipe 10b→drain discharge valve 12→drain pipe 10C.

Warm up the high pressure steam introduction section by repeating this operation.

The temperature of the high-pressure steam introduction part in the conventional warm-up method is
As shown in the figure.

However, this warm-up method generates excessive thermal stress in the high-pressure steam introduction section. Furthermore, since the above-mentioned operations are repeated to warm up the device, it takes a long time to complete the warm-up.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for warming up a BFP turbine that can warm up the high-pressure steam introduction section without applying excessive thermal stress, improve thermal efficiency, and shorten the warm-up time. Another object of the invention is to provide a warm-up device for a BFP turbine that can accurately carry out the warm-up method described above.

[Summary of the invention]

The first invention of the present invention is to introduce steam extracted from the middle of a stage of the main turbine and a high-pressure steam artificial valve into a high-pressure steam introduction section that guides main steam as a power steam source to a steam turbine for driving a boiler feedwater pump. This system is characterized by the fact that either the necessary minimum amount of main steam is introduced from the upstream side of the steam generator to warm it up, and this configuration prevents excessive thermal stress from being applied to the high-pressure steam introduction section. Warm-up is possible, thermal efficiency can be improved, and warm-up time can be shortened.

In addition, the second invention of the present invention is an inlet side of a high-pressure steam introduction section that leads main steam as a power steam source to a steam turbine for boiler feed water and a pump drive, and introduces extracted steam from the middle of a stage of the main turbine. This is characterized in that a warm-up steam system including a steam pipe and a valve are connected, and with this configuration, the warm-up method of the first invention can be carried out appropriately.

The third aspect of the present invention is to supply main steam from the upstream side of the high-pressure steam artificial valve to the inlet side of the high-pressure steam introduction section that guides the main steam as a power steam source to the steam turbine for driving the boiler feed water pump. This invention is characterized by connecting a warm-up steam system equipped with steam piping that partially branches and a valve, and this invention also makes it possible to accurately implement the warm-up method of the first invention. can.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 3 and 4 show an embodiment of the apparatus for carrying out the method of the present invention, in which a high-pressure steam pipe 2b connecting the high-pressure steam artificial valve 3 of the high-pressure steam system A and the high-pressure steam introduction part is heated. Machine steam system C is connected.

The warm-up steam system C includes a steam distribution 7zza connected to the middle of a stage of the main turbine, an electric valve 23 connected to this, a steam pipe 22b connected to this electric valve 23, and a steam pipe 22b connected to this. It includes a check valve 24 and a steam pipe 22C connecting the check valve 24 and the high pressure steam pipe 2b on the downstream side of the high pressure steam artificial valve 3.

Note that the high-pressure steam introduction section is the same as that explained with reference to FIGS. A chest 6 is provided.

Additionally, the warm-up system, including the warm-up steam piping and orifice, has been removed.

Note that other configurations of this embodiment are shown in FIG.
It is similar to that shown in FIG.

Next, an example of the method of the present invention will be explained in connection with the operation of the warm-up device shown in FIGS. 3 and 4.

First, when starting the main turbine, before the high-pressure steam introduction section is warmed up, the high-pressure steam artificial valve 3 of the high-pressure steam system A
, HP-M8V4, and HP-CV5 are fully closed, and the first. The drain discharge valves 8, 9, 11.12 of the second drain system are fully open.

When the electric valve 23 of the warm-up steam system C is opened from this state, low-temperature, low-pressure steam extracted from the middle of the main turbine stage and slightly higher than the warm-up completion target temperature is released as warm-up steam from the steam pipe 22a to the electric Valve 23 → Steam piping 22b → Check valve 24
→It flows through the steam pipe 22C to the high pressure steam pipe 2b, and is introduced into the chest 6 of the HP-MSV4 from this high pressure steam pipe 2b.

Here, since the HP-M8V4 is fully closed,
The warm-up steam is passed from the inside of the chest 6 of P-M8V4 to the first drain system's drain pipe 7a → drain discharge valve 8 → drain pipe 7b → drain discharge valve 9 → drain pipe [7c] to the blow tank. Furthermore, leak steam from the gap between the valve stem 4' of the HP-MSV 4 and the chest 6 passes through the leak steam system 15 and is heat-recovered to the grand steam system.

Meanwhile, the interior of the chest 6 of the HP-MSV4 is gradually warmed up because the warm-up steam is filled with low-temperature, low-pressure steam.

Further, drain generated during warm-up is also discharged to the blow tank through the first drain system.

After warming up the inside of the chest 6 of the HP-M8V4, the HP
-When MSV4 is opened, warm-up steam passes through HP/MSV4 and D
, HP-CV 5 Notie, 1. Introduced inside Toro.

In this state, HP-CV5 is fully closed, so
The warm-up steam is from inside chest 6 of HP-CV5.
Drain piping 10 a of the drain system → drain discharge valve 11
→ Drain pipe 10b → Drain discharge valve 12 → Drain pipe 1
0C and is discharged to the main turbine condenser. Also,
Leak steam from the gap between the valve stem 5' of the HP-CV5 and the chest 6 passes through the leak steam system 16 and is heat-recovered to the ground steam system.

Even if this state is maintained and the temperature of the chest 6 is introduced, even if the main steam is introduced, the chest 6 continuously flows the main steam or the main steam is introduced and stopped many times. Warm up to the temperature.

When the warm-up is completed, 1. The electric drain discharge valves 9 and 12 of the second drain system are fully closed. When these drain discharge valves 9 and 12 are fully closed, warm-up steam is released from HP/MSV4. I(
P-CV5 (D from the gap between valve stem 4' + s' and -y-Nystro 1st. 2nd leak steam system 15.
16 to the grand steam system, no condensate accumulates inside the chest 6.

After the warm-up is completed, when main steam is requested from the BFP turbine 1, the high-pressure steam valve 3 of the high-pressure steam system A is opened, and the high-pressure steam valve 3 of the high-pressure steam system A is opened.
Main steam is vented to the FP turbine 1.

When the main steam is introduced, the warm-up steam automatically stops flowing.

According to the warm-up method of this embodiment, as shown in FIG.
At the start of warm-up, it is possible to warm up gradually without applying excessive thermal stress to the high-pressure steam introduction section. In addition, since the main steam is not used as the warm-up steam and warm-up is performed using extracted air, not only can thermal efficiency be improved, but the warm-up system including the conventional warm-up steam piping and orifice can be improved. The warm-up time can be shortened compared to the warm-up technology that has been removed.

Next, FIG. 5 shows another example of an apparatus for carrying out the method of the present invention, in which a warm-up steam system is provided that bypasses the high-pressure steam large mouth valve 3 of the high-pressure steam artificial valve.

The warm-up steam system includes a steam pipe 25a connected to the high-pressure steam pipe 2a on the upstream side of the high-pressure steam artificial valve 3, an electric valve 26 connected to this, and this electric valve 26 and the high-pressure steam artificial valve 3. and a steam pipe 25b connecting the high pressure steam pipes 2b on the downstream side.

Regarding other configurations of the embodiment shown in FIG. 5,
It is similar to that shown in FIGS. 3 and 4 above.

In the warm-up device of the embodiment shown in FIG. 5, when warming up the high-pressure steam introduction section, the electric valve 26 connected to the warm-up steam system is opened, and the high-pressure steam valve 26 on the upstream side of the high-pressure steam artificial valve 3 is opened. W2a
The necessary minimum amount of main steam is branched from the main steam pipe 25a of the warm-up steam system as warm-up steam, and the warm-up steam is passed from the electric valve 26 to the steam pipe 25b to the high-pressure steam artificial valve. The steam flows into the high-pressure steam piping 2b on the downstream side of No. 3, is introduced from the high-pressure steam piping 2b into the high-pressure steam introduction section, and is warmed up.

When the BFP turbine 1 requests main steam after the warm-up of the high-pressure steam introduction section is completed, the electric valve 26 in the warm-up steam system is closed, and then the high-pressure steam artificial valve 3 is opened.

According to the warm-up method using the warm-up device according to this embodiment, as shown in FIG. can be shortened. In addition, with this warming method, instead of constantly flowing a portion of the main steam as warm-up steam, the minimum amount of main steam necessary for warming is introduced only when warming is necessary. , the warm-up time can be shortened, and thermal efficiency can be improved.

Note that other functions of the warm-up device shown in FIG. 5 and other steps of the warm-up method performed using this warm-up device are the same as those explained with respect to FIGS. 3 and 4 above. It is.

In addition, in each of the above-mentioned embodiments, the warm-up steam system is not limited to one that connects to the high-pressure steam piping 2b connecting the high-pressure steam artificial valve 3 and the HP-MSV 4, and for example, the manual drain discharge valve of the first drain system. Drain piping 7 connecting 8 and HP/MSV4
A connection may be made by providing a connection port in the chest 6 of the HP-MSV 4. In short, any configuration that allows warm-up steam to be introduced to the inlet side of the high-pressure steam introduction section is sufficient.

Furthermore, the valves provided in the warm-up steam system are not limited to electric valves in each embodiment, but may be ones whose opening and closing are controlled by fluid pressure.

Moreover, the above-mentioned warm-up steam system is not limited to one system, and a plurality of systems with different steam conditions may be additionally installed.

〔Effect of the invention〕 .

According to the warm-up method as the first invention of the present invention described above, the high-pressure steam introduction part that guides main steam as a power steam source to the steam turbine for driving the boiler feed water pump has air extracted from the middle of the stage of the main turbine. Warm-up is performed by introducing either the steam that has been heated or the minimum necessary amount of main steam branched from the upstream side of the high-pressure steam artificial valve, so that excessive heat is not generated in the high-pressure steam introduction section at the start of warm-up. It has the effect of warming up without creating stress, and warms up using low-temperature, low-pressure bleed air or the minimum necessary amount of main steam.
In addition to having the effect of improving thermal efficiency, there is also the effect of shortening warm-up time.

Further, according to the warm-up device as the second invention of the present invention, the heating device is provided on the inlet side of the high-pressure steam introduction part that guides the main steam as a power steam source to the steam turbine for driving the boiler feed water pump, in the middle of the stage of the main turbine. Since a warm-up steam system equipped with a valve is connected to a steam pipe that introduces steam extracted from the steam pipe, there is an effect that the method of the present invention can be carried out accurately.

Furthermore, the warm-up device as the third invention of the present invention includes a high-pressure steam artificial valve on the inlet side of the high-pressure steam introduction section that guides main steam as a power steam source to the steam turbine for driving the boiler feedwater pump. Since a warm-up steam system equipped with a valve and a steam pipe that branches part of the main steam from the upstream side is connected, this invention also has the effect that the method of the invention described above can be carried out properly.

[Brief explanation of drawings]

Fig. 1 is a system diagram of an RFP turbine including a conventional warm-up device, Fig. 2 is an enlarged sectional view showing the high-pressure steam introduction section in Fig. 1 and its surrounding system, and Fig. 3 is an implementation of the method of the present invention. FIG. 4 is an enlarged cross-sectional view showing the high-pressure steam introduction section and its rotary system in FIG. 3, and FIG. A system diagram showing another example, FIG. 6 is a diagram showing warm-up characteristics according to the conventional technology shown in FIG. 1, FIG. 7 is a diagram showing warm-up characteristics according to another conventional technology, and FIG. 9 is a diagram showing the warm-up characteristic according to the present invention shown in FIG. 5, and FIG. 9 is a diagram showing the warm-up characteristic according to the present invention shown in FIG. 1...RFP turbine, A...high pressure steam system, B...
...Low pressure steam system, 28~2C...High pressure steam piping, 3
... High pressure steam artificial valve, 4... HP/MSV constituting the high pressure steam introduction section, 5... HP-CV, 6...
・The same chest, 7a to 7C... Drain piping of the first drain system, 8, 9... The same drain discharge valve, 10a to 10
C... Drain piping of the second drain system, 11.12.
・・Drain discharge valve, C ・Warm-up steam system using low-temperature, low-pressure steam, 22a to 22C ・・Steam pipes forming the warm-up steam system, 23・・・Same electric valve, 24・・- Check valve, D... Warm-up steam system using steam branched from main steam, 25a, 25b... Steam piping forming the warm-up steam system, 26... Electric valve. Agent Patent Attorney Masami Akimoto Fig. 1 Fig. 2 riJ b Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Summary 8 Fig. 9 Closing of the anti-Japanese government whirlpool - Harutomo leaving the finances -

Claims (1)

[Claims] 1. Steam extracted from the middle of a stage of the main turbine and the upstream side of the high-pressure steam artificial valve are added to the high-pressure steam introduction section that leads main steam as a power steam source to the steam turbine for driving the boiler feed water pump. A method for warming up a steam turbine for driving a boiler feedwater pump, characterized by introducing either the necessary minimum amount of main steam branched from the main steam and warming it up. 2. A valve is provided on the inlet side of the high-pressure steam introduction section that guides main steam as a power steam source to the steam turbine for driving the boiler feedwater pump, and a steam pipe that introduces steam extracted from the middle of a stage of the main turbine. A warm-up device for a steam turbine for driving a boiler feed water pump, characterized in that a warm-up steam system is connected. 3. On the inlet side of the high-pressure steam introduction section that leads main steam as a power steam source to the steam turbine for driving the boiler feed water pump, there is a steam pipe that branches a part of the main steam from the upstream side of the high-pressure steam artificial valve, and a valve. A warm-up device for a steam turbine for driving a boiler feed water pump, characterized in that a warm-up steam system is connected to the warm-up steam system.